ABSTRACT
This chapter discusses methods for the measurement of particle concentration. It also discusses the concentration measurement of very fine particles suspended in the air. The concentration of particles suspended in air or gas is represented in several ways. The electrical phenomena are also utilized in the measurement of particle concentration. They are the electrostatic charging of particles, piezoelectric effect of crystals, electric capacitance increase of a parallel-plate condenser, and the resonant frequency decrease of microwaves. The attenuation technique is also utilized in the measurement of a mass of particles in a powder bed or particles collected on filters. The chapter describes photo extinction, beta-ray attenuation, piezoelectric vibration, and others that are relatively simple methods for the measurement of aerosol concentration. It also explains the light-scattering method and the condensation nuclei counter for ultrafine particles. Light scattering by an individual particle depends on particle size, the refractive index of the particle, the wavelength of light, and the scattering angle.
